medium importancemedium difficulty6 min

Electromagnetic Induction

Electromagnetic induction is the production of induced current in a conductor when the magnetic field around it changes.

In one line: No change, no induction.

Practice This Concept

Understand it

If the magnetic field linked with a coil changes, an electric current can be produced in the coil.
The change may happen by moving a magnet toward or away from the coil, or by moving the coil in a magnetic field.
The main idea is change in magnetic flux, not just the presence of a magnet.
This principle is used in generators and many induction-based devices.

Example

When a bar magnet is moved into a coil connected to a galvanometer, the needle deflects, showing induced current.

Formula and rule

An induced current is produced only when there is a change in magnetic field linked with the conductor or coil.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

1If the north pole of a magnet is pushed into a coil, the galvanometer needle shows a momentary deflection.
2When the magnet stops, the deflection disappears because the change stops.

Method you can reuse

1Place a coil near a magnet.
2Change the magnetic field by moving one relative to the other.
3Observe a galvanometer deflection.
4Conclude that induced current is produced only during change.
5State that stopping the change stops the induced current.

Sketch it in your answer

Draw a magnet moving into a coil connected to a galvanometer, with arrows showing motion and needle deflection.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

When does a coil produce induced current during electromagnetic induction?

Think first, then show answer

A coil produces induced current when the magnetic field linked with it changes. The change may happen by moving a magnet or by moving the coil, so the field is not the same all the time.

Common wrong answer

Induced current is produced by a stationary magnet near the coil.

Why it loses marks: The field must change.

Don't mix this up

Students often think a magnet alone produces current at rest. Current is induced only when the magnetic field changes.

Exam tip

Use the words change in magnetic field, induced current, and relative motion in exam answers.

Write it in the exam

Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.

How CBSE asks it

Explain the meaning of electromagnetic induction, state conditions for induced current, or describe a galvanometer experiment.

1
Enough for 1 mark
Electromagnetic induction is the production of induced current in a conductor when the magnetic field around it changes.
2
Add for 2 marks
Example: When a bar magnet is moved into a coil connected to a galvanometer, the needle deflects, showing induced current.
3
Add for 3 marks
If the magnetic field linked with a coil changes, an electric current can be produced in the coil.

MCQ Quiz

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